You are HERE >> Mathematics  > Grade 5

Divisibility Rules: No, it's not Cheating!
By Lisa Williams
November 10, 2000

These rules are useful for kids from the time they start division, on. They keep me from using a calculator and most of the time, I can even work it in my head faster than the calulator because of these rules. I use them most when reducing awkward fractions.

 To Divide by ... Cheat Codes 2 A number is divisible by 2 if it ends in 0 or an even number. Example:   40 divided by 2 = 20             3974 divided by 2 = 1987 . 3 A number is divisible by 3 if the sum of the digits is divisible by 3. Example: 321 add 3+2+1= 6 so 321 divided by 3 = 107    2460 add 2+4+6+0= 12 so 2460 divided by 3 = 820 4 A number is divisible by 4 if the last 2 digits are both zeros or if they are divisible by 4. Example:  300 divided by 4 = 75                3548 divided by 4 = 887 5 A number is divisible by 5 if it ends in 0 or 5. Example:  25 divided by 5 = 5                400 divided by 5 = 80 6 A number is divisible by 6 if it is even and divisble by 3. Example: 246 is even and 2+4+6 = 12 so 246 divided by 6 = 41 9 A number is divisible by 9 if the sum of the digits is divisible by 9. Example: 81 add 8 + 1= 9 so 81 divided by 9 = 9      972  add 9+7+2 = 18 so 972 divided by 9 = 18 10 A number is divisible by 10 if it ends in 0. Example: 400 divided by 10 = 40

 Submitted by: Copyright© Lisa Williams I'm a homeschooling mom of 3 elementary school age children. I run a clowning business from my home (Jingles the clown), am pianist for a local church, teach a Sunday School class, teach piano, tutor basic math see Math tutoring and algebra online and I enjoy making people smile.
 Feedback: * *